有用，我用mosonry 框架写的约束，在执行动画时更新约束条件即可

- (void)movingBtnClicked:(UIButton*)btn

{

    self.isLeft = !self.isLeft;

//    [self.view setNeedsUpdateConstraints];

//    [self.view updateConstraintsIfNeeded];

//    [self.view updateConstraints];

    [self updateViewConstraints];

    [UIView animateWithDuration:1 animations:^{

        [self.view layoutIfNeeded];

    }];

}

- (void)updateViewConstraints

{

    [super updateViewConstraints];

    [self.btn mas_remakeConstraints:^(MASConstraintMaker *make) {

        make.size.mas_equalTo(CGSizeMake(100, 100));

        // 在左上角

        if (!self.isLeft) {       

            make.right.equalTo(self.view.mas_right).with.offset(-10);

            make.bottom.equalTo(self.view.mas_bottom).with.offset(-10);

        }else

        {

            make.left.equalTo(self.view.mas_left).with.offset(10);

            make.top.equalTo(self.view.mas_top).with.offset(10);

        }

    }];

}